Infrared photoconductive and photovoltaic effects are observed in Er-doped Si nanoclusters incorporated in a silicon p-i-n slot-waveguide device. These effects are ascribed to deep gap states of Si nanoclusters. The room temperature open circuit voltage of the devices is 290 mV under transmission of guided light at 1.5 μm. A power dependence, with the exponent close to 0.5 and 1 for forward and reverse bias, respectively, has been observed for the photocurrent versus light intensity characteristic. The former is attributed to bimolecular recombination (empty deep gap states) and the latter to linear recombination with the states being populated with electrons.